1. Field of the Invention
This invention relates to new fluorinated benzenesulfonate diacetylene compositions useful in time-temperature history monitoring devices.
2. Brief Description of the Prior Art
Diacetylene compositions, containing at least one conjugated diyne grouping, i.e., --C.tbd.C--C.tbd.C--, and including benzenesulfonate derivatives, are known to be useful in time-temperature history monitoring devices as exemplified in U.S. Pat. No. 3,999,946 (Patel et al. to Allied Chemical, 1976), which is hereby incorporated by reference. As described in the reference, the unique crystal packing and chain alignment of solid monomeric diacetylene compositions, enables them to be polymerized in the solid state by actinic or high energy ionizing radiation, or thermal annealing, thereby producing a colored polymer having a fully conjugated polymer backbone. Generally, the hue and intensity of the resulting observed color is a function of the degree of polymerization, which in turn is a function of the integrated time-temperature history or radiation-dosage history to which the composition has been subjected.
A general characteristic of the solid monomeric diacetylene compositions is that, upon thermally induced solid state polymerization, a gradual increase in the hue and intensity of produced color normally occurs. Advantage can be taken of this characteristic in time-temperature history devices, which are not "on-off" or "go-no-go" type devices, for example, by pretreating the compositions for different time periods and then forming an array in which a gradual change occurs along the array, thus producing a visual moving boundary. Devices of this type are described in U.S. Application Ser. No. 839,542 (filed Oct. 5, 1977, R. Baughman et. al to Allied Chemical). However, these devices normally require an attached color reference chart for ascertaining the extent of the accumulated time-temperature history of the compositions or a highly refined pretreatment procedure meeting rigid quality control standards which can be expensive and add to the total cost of producing such devices.
What is desired in an "on-off" or "go-no-go" device is a composition which does not exhibit a gradual increase in developed hue and intensity, but one that remains colorless, or nearly so, until the desired known time-temperature history interval or shelf-life of an article being monitored has been reached, whereupon a striking color change occurs just prior to the expiration of said interval. Such a composition should undergo a small degree of polymerization before a certain time-temperature history interval is reached, termed a "long polymerization induction period," and when the desired interval is reached, the composition should exhibit an accelerated rate of polymerization, termed as "autocatalytic polymerization effect". The mechanisms underlying the polymerization inductive period and autocatalytic effect are not clearly understood.
Only one diacetylene composition in the prior art is known to exhibit this behavior, the bis(p-toluene sulfonate) of 2,4-hexadiyn-1,6-diol, referred to herein as PTS, whose properties upon thermal polymerization are described in the article Die Makromolekulare Chemie Vol. 145 (1971) pp 85-95 by Gerhard Wegner. From this teaching it could be inferred that para-substituted benzene sulfonates of diacetylenic diols, in general, might exhibit relatively long polymerization induction periods coupled with autocatalytic polymerization effects in the region of a desired integrated time-temperature history of an article.
However, the reference Acta Cryst. (1978) B-34, pp. 143-147 by J. J. Mayerle and T. C. Clark, discloses that the bis(p-chlorobenzenesulfonate) of 2,4-hexadiyn-1,6-diol does not undergo solid state polymerization upon thermal annealing or exposure to X-ray irradiation. The authors indicate that the particular packing characteristics of the crystals, which are dominated by non-bonded Cl-Cl and Cl-C (phenyl) interactions, which in turn interfere with monomer packings, are responsible for interfering in the solid-state polymerization process of the solid compound.
We have independently shown that bis(p-bromobenzenesulfonate), bis(p-nitrobenzenesulfonate), bis(p-methoxybenzenesulfonate) and bis(2,4,5-trichlorobenzenesulfonate), of 2,4-hexadiyn-1,6-diol, are all inactive to solid state polymerization upon thermal annealing.
Thus, the implied assumption in the prior art, that all halogenated benzenesulfonates of diacetylenic diols are capable of undergoing solid state polymerization is misleading.
What is needed and what the prior art does not describe the halogenated benzenesulfonate derivatives of acetylenic diols, preferably a definable class of such diacetylenes, capable of undergoing solid state polymerization and preferably exhibiting relatively long polymerization induction periods coupled with autocatalytic polymerization effects.